Blockstream is a blockchain technology company co-founded by Adam Back, Gregory Maxwell, Pieter Wuille and others, and led by Adam Back. Blockstream is one of a number of institutions that provide funding for the development of Bitcoin Core, the predominant network client software.

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The company is focused on developing bitcoin applications: specifically sidechains, as well as other applications.[2][3] Blockstream has raised $76M to date from investors including Horizons Ventures and Mosaic Ventures.[4][5][6] Blockstream employs several prominent cryptographers, bitcoin developers, and industry veterans,[1] including Adam Back (CEO, Blockstream), Pieter Wuille (Bitcoin Core developer), and Samson Mow (CSO).[7][8][9] Blockstream is one of the largest contributors of funding for Bitcoin Core.[10]

On October 12, 2015, Blockstream announced the release of its Liquid sidechain prototype which could allow for the transfer of assets between the sidechain and the main blockchain.[11][12][13] On October 11, 2018, a production-ready implementation of the sidechain was officially launched, called the Liquid Network.[14] Blockstream produces software that facilitates interoperability between the Bitcoin main chain and the sidechain.[15][page needed] Blockstream claims that Liquid reduces the delays and friction involved in a normal transfer of bitcoin. Blockstream asserts participating exchanges–including Bitfinex, BitMEX and OKCoin[14]–can make near-instant exchanges between their accounts and orderbooks.[16] The company has proposed that the Liquid sidechain, which is a pegged sidechain, be added to the bitcoin protocol.[17][18][19] The source code for sidechains has been released on an open source basis.[20]

In 2017 Blockstream announced the availability of one-way satellite broadcasting of the full Bitcoin blockchain.[21] The company plans to earn fees for value-added services on the network.[21] In 2018 Blockstream extended the Bitcoin satellite network[22] to four satellites across six coverage zones, adding Asia and Pacific region coverage, and released API specifications to allow users to send data over its network. The network as of 2019 is only a one-way network and the user still needs a connection to the Bitcoin network to send transactions, which can include SMS gateways [23] or higher cost internet which would be expensive for receiving full Bitcoin block data, but is cost effective to send a single transaction.

Blockstream hired Rusty Russell, a developer well known for his work on the Linux kernel, to develop an implementation of the Bitcoin Lightning Network (LN). Russell has a four-part LN explanation on his blog.[24] The Lightning Network proposes to reduce transaction costs by allowing nodes to hold some transaction data in the cache before submitting it to the chain.[25]

In May 2017, Segregated Witness activated on Litecoin, enabling the Lightning Network to be used.[26] In May 2017 Christian Decker of Blockstream sent the first microtransaction using Lightning on Litecoin.[27]

Blockstream's implementation of the Lightning Network is called c-lightning and is used to power Bitcoin payment processing on the official Blockstream e-commerce store.[28]

In April 2017, Blockstream released a paper on Confidential Assets,[32] an extension of Confidential Transactions (which is itself derived from an Adam Back proposal for homomorphic values applied to Bitcoin[33]). Confidential Assets was later adopted in both the Liquid Network and Elements, and is now known as Issued Assets.[34][unreliable source][35][non-primary source needed]

Among other contributions:

We begin by describing an efficient rangeproof for Pedersen commitments over the interval [0, mn − 1], which has total size proportional to 1 + nm, using a variant of a folklore bit-decomposition based rangeproof, in which numbers are expressed in base m and each digit is proven to lie in [0, m − 1] using a ring signature.